It is known in the art that various products may be produced by reacting one or more reactants in the presence of an metal-organophosphorus ligand complex catalyst. However, stabilization of the catalyst and organophosphorus ligand remains a primary concern of the art. Obviously catalyst stability is a key issue in the employment of any catalyst. Loss of catalyst or catalytic activity due to undesirable reactions of the highly expensive metal catalysts can be detrimental to the production of the desired product. Moreover, production costs of the product obviously increase when productivity of the catalyst decreases.
For instance, a cause of organophosphorus ligand degradation and catalyst deactivation of metal-organophosphorus ligand complex catalyzed hydroformylation processes is due in part to vaporizer conditions present during, for example, in the vaporization employed in the separation and recovery of the aldehyde product from the reaction product mixture. When using a vaporizer to facilitate separation of the aldehyde product of the process, a harsh environment of a high temperature and a low carbon monoxide partial pressure than employed during hydroformylation is created, and it has been found that when a organophosphorus promoted rhodium catalyst is placed under such vaporizer conditions, it will deactivate at an accelerated pace with time. It is further believed that this deactivation is likely caused by the formation of an inactive or less active rhodium species. Such is especially evident with organophosphites when the carbon monoxide partial pressure is very low or absent. It has also been observed that the rhodium becomes susceptible to precipitation under prolonged exposure to such vaporizer conditions.
For instance, it is theorized that under harsh conditions such as exist in a vaporizer, the active catalyst, which under hydroformylation conditions is believed to comprise a complex of rhodium, organophosphorus ligand, carbon monoxide and hydrogen, loses at least some of its coordinated carbon monoxide, thereby providing a route for the formation of such a catalytically inactive or less active rhodium. Accordingly, a successful method for preventing and/or lessening such degradation of the organophosphorus ligand and deactivation of the catalyst as occur under harsh separation conditions in a vaporizer would be highly desirable to the art.